1. Field of the Invention
This invention relates to tools of the type used by toolmakers, diemakers and others to determine the deviation from a predetermined angle of a manufactured part.
2. Description of Related Art
The precision required for many machine parts is extremely critical. The precision may be required for either an inside angle or an outside angle. Although there are known devices for measuring either an inside or an outside angle, such as that disclosed in U.S. Pat. No. 3,380,165, most are intended for one use or the other. Even devices such as that disclosed in U.S. Pat. No. 3,380,165 generally are most effective in measuring either an inside angle or an outside angle.
A related class of gauges are those intended to measure deviation from proper alignment of cylinders such as U.S. Pat. No. 1,852,760. In application, these devices combine the features of measuring both inside and outside angles although they measure what is substantially an inside angle. Also related to the class of angle gauges and capable of providing an indication of deviation from specified angles are devices such as the mechanic's square of U.S. Pat. No. 2,448,440, draftsman's squares, and carpenter's squares. The reliability of these devices however is a function of the precision with which they are manufactured, the care that has been taken with them over their period of use, and integral angles to which they are manufactured such as right angles and 45.degree. angles. However, devices of this type by themselves, only indicate deviation. They are unable to provide a measure of that deviation from the desired angle.
Cylinder or cylinder type gauges have provided one solution to the need for deviation measurement devices. These gauges are used to measure an inside angle, that is the angle between a horizontal surface and an essentially vertical surface. However, they can be used for measuring what is a workpiece outside angle by placing one surface face of the workpiece angle on a horizontal surface and using the cylinder type square to measure the deviation of the substantially vertical surface defined by the second face of the angle. Cylinder type gauges include a base leg that is placed on the horizontal surface and a vertical leg, normally cylindrical, that is placed against the vertical surface to be measured. The gauge may be mounted in or on either the base or vertical leg but is most normally found on the vertical leg. U.S. Pat. Nos. 3,273,252; 3,570,132; 3,688,412; and 4,096,634 disclose squareness gauges of this general type.
Related to this method of measurement is the indicating square of Leszak, U.S. Pat. No. 2,397,280, which is a cross between a carpenter's square with one edge adjustable and the operation principles of a cylinder square. In Leszak, the adjustable edge is in contact with a dial or gauge for measuring deviation.
An inherent disadvantage of these known cylinder gauges is that they require a smooth horizontal surface on which the workpiece must be placed for their use. Further, that surface must be of sufficient size to provide a stable footing for the horizontal leg or arm of the square in addition to the workpiece.